They could have been Slack if they didn't transmogrify it into a social media platform (Google+) and then throw out the baby with the bathwater when it failed.
I’m talking about something much more fundamental, the entire company would pretty much implode within 24 hours (or at most a week) if they couldnt verify who is who.
You're really giving credit in the wrong areas. Google is impressive for its ability to exist beyond the point of dysfunction. It's simply not the case that any Googler would need to verify the identity of any other any more than it is necessary for every server to verify the identity of every other. They only need to verify the identify of the tiny subset they are communicating with at any given time. This doesn't mean everyone has access to a coherent org chart, or that one even exists.
> Ask their managers? But then how do their managers verify?
It's a hierarchical org chart. If you're really not sure ask Sundar.
It's likely any Googler can verify the identity of any other by looking up their username but it's unlikely that the same tool would do something like tell you how the YouTube recommendation algorithm works or who would know that.
They will know the names of frequent collaborators and something about the scope of relevant work but it's not like everyone at Google needs intimate knowledge of every workstream. At that scale it's unlikely anyone has the full picture.
Going from person to team is fairly easy, but going from team to person is hard. That is, you can often confirm a person is a member of a particular team or organization just by looking up their email address, but the reverse direction of finding the right point of contact for a particular team or organization can be difficult.
Searching for the tree root starting from a tree leaf is easy, but searching for the right leaf starting from the root takes a lot more effort.
Aside from the huge array of stuff they've built in house, the "List of mergers and acquisitions by Alphabet" wikipedia page has 264 entries. Some of those bought other companies.
>If googlers dont have an internal org chart they can check, then how do they verify who is on what team?
You really think some guy in some offshore office for low pay, with his boss hounding at him about his KPIs, is going to go out of his way to bother with this?
Now you're getting a clue why Google had like 3-4 competing communication tools at some point lol